memcmp() can return values other than -1, 0, and +1 but tp_compare
must not.
diff --git a/Misc/NEWS b/Misc/NEWS
index 04549b9..24b1645 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -12,6 +12,8 @@
 Core and builtins
 -----------------
 
+- Bug #1536786: buffer comparison could emit a RuntimeWarning.
+
 - Bug #1535165: fixed a segfault in input() and raw_input() when
   sys.stdin is closed.